This invention relates to the field of prosthetic dentistry, and more specifically to the fabrication and fitting of partial fixed and removable dentures such as crowns and bridges.
Prostheses made in accordance with the well established technique only approximate an ideal fit, for which reason the useful life, or the ability to preserve the life of the teeth to which affixed is also limited. The principal problem is the inability to produce a prosthesis which will perfectly fit the prepared surfaces of a tooth.
The best results under the established technique are obtained with alloys containing a high content of a noble metal such as gold. Unfortunately, the advantages are counterbalanced by the disadvantage of very high cost.
Other and cheaper alloys such as chrome-cobalt or chrome-nickel are in common use for the fabrication of dental prostheses. The problem with the cheaper alloys is the same as in many other arts; that is, nothing works as well as gold.
The principal problem is one of misfit, especially where the edge of the prosthesis meets the margin of the prepared tooth. The better the fit between the prosthesis and the prepared tooth surfaces, the less likely bacteria can enter and destroy the tooth. It is rather common that the patient will not even suspect that anything is wrong until the prosthesis becomes detached, at which time it is discovered that the tooth has decayed under the prosthesis and may well be beyond further repair.
The misfit between a prosthesis and the supporting surfaces on a tooth cannot be corrected by the cement holding it in place. The cement or luting agent may appear to be a fix; however, it is soluble in oral fluids and will eventually admit bacteria.